This invention relates in general to electrical storage batteries and, more specifically, to high efficiency batteries using a metal anode, a sulfur containing cathode and an electrolyte solution comprising metal and sulfur ions.
A great many different battery structures and component compositions have been developed. Many are very effective for particular applications. Today, there is considerable interest in high capacity batteries with short recharge times for use in such applications as electrically powered automobiles. A number of different types of batteries have been proposed, or are in development for this type of application.
At present, lead-acid batteries are used because of their low cost and well developed technology Unfortunately, these batteries are heavy, consume considerable space, have poor energy storage and a short useful life. Typically, these batteries will power a small automobile for up to about 90 miles at low to moderate speeds, then require around 10 hours recharge time, although some advanced charging system may reduce the recharge time to around 2 hours.
Nickel-iron and nickel-cadmium batteries are also available now, with slightly greater duration of use and slightly shorter recharge time in automobile applications. They have a longer life and are compact compared to lead-acid batteries. However, the present cost of these batteries is relatively high and recharging is generally required after about 120 miles of driving.
Nickel-metal hydride batteries are under development and may be ready for automobile applications shortly. Miles between recharge cycles is approximately double that for lead-acid batteries and with relatively expensive charging systems, they can be recharged in as little as one hour. While energy storage is not great and costs are presently uncertain and likely to be high, at lest in the short run, these batteries have long lives and are maintenance free.
Other types of batteries, such as sodium-sulfur, zinc-air, lithium polymer, lithium-aluminum and iron-disulfide are in initial stages of development. Developers hope to achieve about 250-400 miles between recharges in automobile use, with recharge time of 5 hours or less. These batteries are expected to have high storage capacity. Unfortunately, some require high operating temperatures, and may not tolerate rapid recharging well.
Therefore, there is a continuing need for inexpensive reversible batteries having high energy storage, light weight and with rapid recharge ability for applications such as electrically powered automobiles.